Contact means



June 29, 1954 Q HUETTEN 2,682,594

CONTACT MEANS Filed Nov. 28, 1950 f7 T TURNEY Patented June 29, 1954 CONTACT MEANS Clarence Huetten, lIndianapolis, Ind., assignor tol P. R. Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware Application November 28, 1950, Serial No. 197,965

The present invention relates to electrical circuit controllers such as vibrators, ignition contact breakers, and various other types of conA tactors, and has specific pertinency to such apparatus and methods directed to provide improved contact structures for devices of this character.

The contact structure of the present invention relates particularly to circuits utilizing circuit breakers employing a contact arm which is adapted through the use of a rotary cam to carry the contacts, per se, into and out of engagement with a cooperating stationary contact. The contacts used in these ignition circuits and for `vibrators, etc., heretofore employed, presented problems usually resulting from difficulties of high interface resistance, contact transfer and slow speed of contact separation. By the present invention there is provided Va contact structure which is adapted to overcome the above dilculties.

The present invention, therefore, provides a novel form of contact structure constructed so as to offer a substantially compliant or flexible mating surface of substantially thin cross-section. As a result thereof, 'the problem of transfer is substantially lessened. The structure, as hereinafter described, limits transfer, contact bounce, and permits a faster break velocity forthe contacting element.

It is, therefore, an object of the present invention to provide a novel contact structure which is readily fabricated, easily assembled, inexpensive and effective in preventing inefficiency resulting from contactors showing early contact failures as a result of transfer of contact material.

Still another object of the present invention is to provide an improved contact for ignition circuits wherein the efciency of said circuit is increased because of the lessened high interface resistance and contact transfer resulting from the novel structure of the contact invention.

Still another object of the present invention is to provide a contact for use with contact breakers wherein the contact element is provided with a substantially compliant surface so that an improved type of make and break relation is obtained between said contact and an associated xed contact.

Still another object of the present invention is to provide a contact structure characterized by improved characteristics Aof interface resistance, contact transfer and speed of separation;

The invention, in another of its aspects, relates to novel features of the instrumentalities de- 4 claims. (c1. 20o-166) scribed herein for vteaching the principal object ofr the invention and to the novel principles em-` ployed in the instrumentalities whether or not these features and principles may be used in the said object and/or in the said field.

Referring to the drawings,

Fig. l is a plan view of the improved contact including as a portion thereof a compliant face or surface of the present invention, and as adapted to be used with an electrical circuit breaker; the embodiment being shown having a cylindrical shape with its base being welded to the contact arm at the periphery thereof;

Fig. 2 is a longitudinal, cross-sectional view of the embodiment of the present invention of the improved contact make and break device shown in Fig. l, taken along line 2 2 thereof and as adapted to illustrate the novel structure of the contact element therein;

Figs. 3 and 4 are illustrations of the structural configuration of the contact used in Figs. 1 and 2 as adapted to illustrate the substantially hollow structure of the contact;

Fig. 5 is a profile view of an alternative embodiment of the contact structure of the invention showing the configuration of the said structure as being of a pyramidal construction having separated triangular mating sections, and

Fig. 6 is a cross-sectional view of the contact structure shown in Fig. 5 as taken along line 6 6 thereof.v

Referring to the drawings, the present invention provides means for affording a contact structure which may be used in ignition circuits, vibrators, etc., to improve the characteristics which relate to interface resistance between the moving contact and its associated fixed contact element. The novel contact minimizes losses due to interface resistance, contact transfer and slow speeds of separation, By the structure of the contact here described, a contact is provided which allows for the limiting of contact transferor migration of the contact material during the operation of its incorporating device.

The contact consists of a thin sheet of contact material such as tungsten or molybdenum punched and formed as illustrated. The contact may be fastened at its peripheral area such as by welding or clamping while the central structure is the actual contacting surface.

Heretofore, although in many devices only a small portion of the contact material was needed,

. greater thicknesses were used for convenience in the event transfer or erosion occurred over a relatively small area, the contact might mate with the base metal if the contact material were too thin and as a result of which high resistance resulted. In the present novel contact the transfer from it to an associated mating Contact is limited by the thickness of the contact itself. At the same time there is a small space between the contacting surface and the base so that as the compliant member defiects it will maintain contact with the mating surface even though the transfer spike may go through to the base material.

In the case where transfer is such as to deposit material on the contact, the build up of thetransfer is limited by the flexing of the contact surface.

Further, the flexing contact surface may stress the transferred material so that it may fall oi as erosion dust. In addition a slight radial sliding action will occur tending to shear off larger transfer spikes and keep the mating surfaces relatively free of oxides, etc.

Contact transfer and erosion and contact heating vary of the order of the currentl squared'. Thus, as described and shown in Figs. 5 and 6; the separated members assure a larger number of contacting spots and since there will be some current division between the spots the maximum current through a particular spot is, in general, less, and hence the effects of contact transfer, erosion, and heating are reduced.

Referring to Figs. 1-4, the contact of the invention is constructed ofv a thin sheet of contact material formed into a cylindrical cupola or 'natlike shape which may be welded to a support at its periphery, the contacting area thus being unsupported by any base metal. The contact it comprises a top face or disc H adapted to make contact with an associated xed contact l2 supported on a bracket I3 of the circuit breaker. The contact element l has its face il raised a substantial distance from the contact arm i4 to which it is connected by means of a cylindrically shaped side Wall structure i5. The entire contact, including the face portion and the side wall portion, is welded to the contact arm 44 at its periphery I1. As illustrated in Fig. 4, the contacting area or face li is unsupported' by any base metal and presents a substantially hollow structure. As an aid in preventing oscillations, a dampening structure 30 may be included with contact l0.

As a result of the above construction, contact transfer or migration is limited to the thickness of the contact material. This not only limits the height of such transfer but forces a better utilization of the contact material. It has been found, when attempts are made to limit transfer by supporting a thin contact on a base metal, transfer occurs until the transfer pip hits the base metal and high resistance results. The present contact structure, however, overcomes this difliculty. The contact structure described is readily fabricated, easily assembled and is inexpensive. The novel structure of the present invention has been found effective in preventing early contact failures as a result of contact transfer or migration.

In Figs. 5 and 6 the contact having a yielding surface is shown as comprising a pyramidal construction 20, having separated triangular sec- .Q

tions or faces 2 I, 22, 23, 24. Each of the sections has been substantially raised above the contact arm itself so as to approach a confiuxing point or apex 25. The separate triangular faces such as 2| and 22 are adapted to be connected to the contact arm peripherally as at 2l by means of welding the said sections to the arm. rlhus the structure of the contact has a greater compliance than usual and which affords means for overcoming contact transfer or migration since, as pointed out above, contact transfer or migration has been substantially lessened because of the re` duced thickness of the contacting area.

The lpresent invention of a contact With a compliant surface, as described above, is merely illustrative and not exhaustive in scope and since manyvvidely different embodiments, of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interpreted asr illustrative and not in a limiting sense.

What is claimed is:

l. A contact structure for electrical circuit breakers comprising in combination, a stationary contact, an actuating member movable toward or away from said stationary contact, a main contact movable with said actuating member with respect to said stationary contact, said main contact comprising an element having a iiexible tip substantially spaced from said actuating member, said element having the geometric configuration of-a pyramid including several yieldable and resilient triangular sections and Wherein said pyramid is substantially hollow and is connected to said actuating member'only at the base periphery thereof.

2. A contact structure for electrical circuit breakers comprising in combination, a stationary contact, an actuating member movable toward or away from said stationary contact, a main contact movable with said actuating member with respect to said stationary contact, said main Contact comprising a hollow compliant member having the configuration of a pyramid, said pyramid having a'plurality of yieldable and resilient triangular conjoining faces whereby contact is made between the main Contact and the fixed contact substantially at the apex thereof.

3. An electrical contact comprising a hollow member, said hollow member having the configuration of a pyramid and including a multiplicity ofyieldable triangular sections converging to a point, said point being the contacting area for said contact so as to reduce contact transfer or migration during the operation thereof.

4. A hollow electrical contact comprising a plurality of yieldable triangular shaped sections, each of said sections adapted to be connected to la support at a periphery of each of its sides, and all of said triangular shaped sections converging to a point to form a contact area for said contact to provide means for lessening contact transfer or migration during the operation of said contact.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 953,306 Taylor Mar. 29, 1910 V2,216,510 Burns Oct. 1, 1940 2,277,111 Johnson Mar. 24, 1942 

